Appendix V. Support for GLX in
Xinerama

This driver supports GLX when Xinerama is enabled on similar
GPUs. The Xinerama extension takes multiple physical X screens
(possibly spanning multiple GPUs), and binds them into one logical
X screen. This allows windows to be dragged between GPUs and to
span across multiple GPUs. The NVIDIA driver supports hardware
accelerated OpenGL rendering across all NVIDIA GPUs when Xinerama
is enabled.

To configure Xinerama: configure multiple X screens (please
refer to the XF86Config(5x) or xorg.conf(5x) manpages for details).
The Xinerama extension can be enabled by adding the line

Option "Xinerama" "True"

to the "ServerFlags" section of your X config file.

Requirements:

It is recommended to use identical GPUs. Some combinations of
non-identical, but similar, GPUs are supported. If a GPU is
incompatible with the rest of a Xinerama desktop then no OpenGL
rendering will appear on the screens driven by that GPU. Rendering
will still appear normally on screens connected to other supported
GPUs. In this situation the X log file will include a message of
the form:

(WW) NVIDIA(2): The GPU driving screen 2 is incompatible with the rest of
(WW) NVIDIA(2): the GPUs composing the desktop. OpenGL rendering will
(WW) NVIDIA(2): be disabled on screen 2.

The NVIDIA X driver must be used for all X screens in the
server.

Only the intersection of capabilities across all GPUs will be
advertised.

X configuration options that affect GLX operation (e.g.: stereo,
overlays) should be set consistently across all X screens in the X
server.

Known Issues:

Versions of XFree86 prior to 4.5 and versions of X.org prior to
6.8.0 lack the required interfaces to properly implement overlays
with the Xinerama extension. On earlier server versions mixing
overlays and Xinerama will result in rendering corruption. If you
are using the Xinerama extension with overlays, it is recommended
that you upgrade to XFree86 4.5, X.org 6.8.0, or newer.